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Software development life cycle (SDLC) models illustrate ways to steer through the demanding and intricate process of software building. When choosing a model, you must consider the ability to meet the stakeholder’s expectations, timeframe, budget available, and the project’s quality.

More than 50 recognized SDLC models are in use today. Each having its benefits and drawbacks. Keeping in mind that not all are perfect, we will discuss 8 popular models in this blog. After reading you should have a better understanding of their core features and essence.

The outline

SDLC models can be organized into groups. This is reliant on what kind of bonds are established between the development team and the client, and how they manage workflow in the organization.

Types of SDLC models and what projects each supports best

Waterfall

This process moves in a cataract mode through all development stages (analysis, design, coding, testing, deployment). Each stage is stringently recorded and has distinct deliverables.

This is a continuous process, so the previous stage has to be fully completed before the next stage starts. For example, there is no skill to evaluate software until the last development stage is finished which results in high project risks and unpredictable project results.

Project examples:

• Projects with the need for conventional budget and timelines, and sterner control.

• Projects where infamous technology stack and tools are used.

• Projects that you must abide by several rules and regulations.

• Small or mid-sized projects with unchanging and lucidly outlined requirements 

• Projects where a well-known technology stack and tools are used.

  
  
  

Validation and Verification model

The Validation and Verification model is also known as the V-model. This model involves each stage having a corresponding testing activity. The V-model is considered as one of the most expensive and onerous models because its workflow organization involves extraordinary quality control.

Furthermore, changes during development are still difficult and expensive to implement, even though mistakes in requirements specifications, code, and architecture inaccuracies can be discovered early.

Project example:

• Projects where failures and downtimes are deplorable.

  
  
  

Incremental and Iterative model

In the Incremental model, the development process is divided into several iterations. New software modules are attached with no or little change in earlier modules. The development process can either be parallel or sequential. Sequential development involves reiterated cycles which can make the project long and costly while parallel development enhances the speed of delivery.

With Iterative development, software increasingly gains more intricacy and comprehensive features set up until the final system is complete. Software design remains consistent as each iteration builds on the prior one.

From the start of the project, there is no need for a full specification and small changes to prerequisites are possible during the development process because the software is delivered in parts.

Since further integration of the delivered software part can become an issue, major requirements must be defined in the beginning as they cannot be changed completely.

This model is concerned with customer involvement because of the possible need for small requirements adjustments during the development process.

Project example:

• Large, mission-critical enterprise applications that rather consist of loosely coupled parts, such as microservices or web services.

  
  
  

Spiral model

The Spiral model puts much emphasis on comprehensive risk appraisal. Therefore, you’ll need to involve people with a strong background in risk assessment, to enable you to garner the benefits of the model to the fullest.

A typical Spiral reiteration starts with 4 principal activities - thorough planning, risk analysis, prototypes creation, and evaluation of the previously delivered part. Repeated spiral cycles tend to extend project timeframes and can last around 6 months.

This model demands intensive client involvement. The client can be involved in the examination and review stages of each cycle. The client’s adjustments are not acceptable at the development stage.

Project examples:

• Research and development activity.

• Introduction of a new product or service.

• Projects with ambiguous business needs or large-scale innovation requirements.

• Projects that are large and complicated.

  
  
  

The Rational Unified Process (RUP)

The Rational Unified Process (RUP) is a combination of linear and iterative frameworks. It divides the development process into 4 phases – inception, elaboration, construction, and transition. Except for Inception, each phase is commonly done in several iterations. All basic activities; design, requirement, and so forth, of the development process are done in correspondence across these 4 phases, though with distinctive force.

RUP helps to build stable and flexible solutions. Depending on the project needs, the degree of client involvement, documentation intensity, and iteration length may vary.

Project example:

• High-risk and large projects, especially, the fast development of high-quality software.

  
  
  

The Agile group

The rest of the SDLC models we will be discussing falls under the parasol of the Agile group. Recently, organizations employ the models under the Agile group or Agile approach in their IT projects. At the center of Agile are reiterative development, early customer feedback, and intensive communication.

To deliver a complete working software version, every Agile iteration typically takes several weeks. The models of this group pay less attention to detailed software documentation and instead put more focus on testing activities and delivering a functioning part of the application quickly.

This model fosters quick development, however, it prolongs the transfer to the support team. Along with making its maintenance more complex as more time is spent to find the problem when there is no specified software description.

Agile is focused on close cooperation both across the team and with the clients. Stakeholders assess the development progress and ensure alignment with user needs and business goals at the end of each iteration. This allows stakeholders to re-evaluate the priority of tasks for the future iteration to ultimately increase the return on investment (ROI).

As one of its characteristics is frequent releases, Agile models include continuous software improvements with easy fixes and changes. It also allows quick updates,feature addition, and helps to deliver applications that satisfy users’ needs better. However, it is difficult to accurately quote the budget, time, and resources required for the project due to the lack of detailed planning and openness.

Project examples:

• Large projects that are easy to split into small functional parts and can be developed increasingly over each iteration.

• Mid-sized projects in custom software development where business prerequisites cannot be confidently converted to detailed software requirements.

• Startup initiatives where end-users’ early feedback is required.

Agile comes with varying aspects and we will showcase three: Scrum, Extreme Programming, and Kanban.

Scrum

With Scrum, the sprints (reiterations) are preceded with comprehensive planning and previous sprint evaluation. They are usually 2-4 weeks long. After the sprint activities have been defined, no changes are allowed. It is probably the most popular one from the Agile group.

Extreme Programming (XP)

As for Extreme Programming (XP), a standard iteration usually lasts 1-2 weeks. If the team has not started to work with the relevant software yet the model allows changes to be introduced even after the iteration’s launch. The delivery of quality software can be complicated with such flexibility. To mitigate the problem, XP involves the use of pair programming, test-driven development and test automation, continuous integration (CI), small releases, simple software design, and recommendations to follow the coding standards.

Kanban

With Kanban, its key feature is the absence of prominent iterations and they are kept quite short (‘daily sprints’) if used at all. As an alternative, the emphasis is positioned on plan visualization. The team provides a clear illustration of all project activities, their number, responsible persons, and progress through the Kanban Board tool.

This intensifies transparency to help estimate the most vital tasks more accurately. Also, a new change request can be initiated at any time because the model has no separate planning stage. Clients can verify the work results whenever they like because communication with the clients is a continuous process. Also, the meetings with the project team can occur on a daily basis. The model is frequently used in projects on software support and evolution due to its nature.

Are you ready to start?

Before choosing a Software Development Life Cycle SDLC model you must consider the type of project, the resources available, and the circumstances surrounding the project. Then you are able to compare the models in terms of core features – time, cost, and quality. This will allow you to make a better decision in choosing the appropriate model.

If you’re interested, please contact us and we will get back to you with more information on software development!